The latest plan to ease Detroit-Windsor border congestion is a $400 million proposal to convert a railroad tunnel beneath the Detroit River into a roadway for international truck traffic near the Ambassador Bridge, The Detroit News reports.

The proposal also includes a new underwater tunnel for rail traffic. The project is seen as speeding border traffic slowed by post-September 11 security checks and meeting the demands of growing trade between the United States and Canada.

The Detroit River Tunnel Partnership, a joint venture between Canadian Pacific Railway and Borealis Transportation Infrastructure Trust, said it planned to convert an existing, twin-tube rail tunnel it owns in southwest Detroit into a truck corridor.

A new, single-tube rail tunnel would be built nearby.

Michael Sheahan, general manager of the Detroit River Tunnel Partnership, said the project also would require seven miles of new roads to link to the converted truck tunnel, located behind the vacant Michigan Central Depot at Michigan Avenue and 14th Street, to I-75 in Detroit and Highway 401 in Windsor.

The project could be completed within five years, pending government approvals on both sides of the border. Money for the project is expected to be raised by the Borealis Transportation Infrastructure Trust, owned by the Ontario Municipal Employees Retirement System, which has a $50 billion pension fund.